Be the hero at your next hackathon with this foldable cnc. When the line for the laser cutter is four teams deep, you’ll come out ahead. It might even be accurate enough to pop out a quick circuit board. Though, [wwwektor] just wanted a CNC that could be taken from storage and unfolded when needed. Sit it on a kitchen table and cut out some ornaments, or hang it from the front door to engrave the house’s address. Who needs injection molded chrome plated numbers anyway?
It’s based around tubular ways, much like other 3D printed CNCs we’ve covered. The design’s portable nature gives it an inherently unstable design. However, given the design goals, this is reasonable. It uses timing belts, steppers, and ball bearings for its movement. The way the frame sits on the table it should deal with most routing tasks without needing adjustment to stay in plane with the surface it’s set-on. As long as you don’t need square edges.
There’s a video of it in operation after the break. We love these forays into unique CNC designs. We never know what new idea we’ll see next.
Thanks for the tip [Dominik]!
is there no way to increase stability of the design?
There is and it’s something I’ve experimented with in the past. Instead of using two rails on the extruder assembly and posts you use three, Making one of those rails a screw will also allows a more stable, if significantly slower, milling head. It would also be possible to use tensioned wires to increase the rigidity of the structure, but they would have to be re-tensioned every time the CNC was set up. If your interested in CNC check out my 3D CNC toolchain over on hackaday.io https://hackaday.io/project/9867-cnfr33d I haven’t been able to test it yet as I’m still getting my CNC setup (waiting for parts to come), but it might be worth a look.
I made a low quality CNC something like this in the mid 90’s when CNC wasn’t well known. I ran it with the a program written in the basic that came with DOS (QBASIC?) via direct port read / writes to the LPT (parallel) port.
What I found was that you need to keep bearing *and bearing surface* under tension by distributing the bearings further.
I was using simple geometric extrusions but the principle is still the same for tubing.
If you have three bearing at one distance along a tube then they have no resistance to play in one plane. Of course putting another three bearings at another distance will help dramatically but not having tension on the bearing and bearing surface will mean that there is always play in the system that is additional to any play that results from structural flex *AND* this play will be evident even at low loads as next to zero force is needed for it to occur.
So instead of having three bearings at point “A” and three bearings at point “B” you can have 2 bearings at points “A” and “B” and then place another bearing half way in between. Put this last bearing under so much load that it causes a load on the other bearings and the bearing surfaces by tending (or attempting) to flex the structure that forms the bearing surface.
The basic rule here is triangulation.
Imaging three bearings placed to match 20mm tubing and then you put 16mm tubing in – they will flop everywhere and while adding a second set of unmatched bearings will reduce the play – it does *NOT* remove the play that results from the mismatch.
Now do the same mental exercise with the system I described and you get a system that is designed for 20mm tubing that *will* also work with the smaller tube.
You’re missing a word in your headline and throughout the article. It’s the word that is supposed to follow “CNC”. “BE A HERO AT YOUR NEXT HACKATHON WITH A FOLDABLE CNC [ROUTER]”
Honestly, reading it reminds of when people used to say things like “I think my Microsoft is broken”.
“What do you mean, ‘your Microsoft’?”
“You know, the Internet. That blue E?”
What software toolchain is in use?
Adding brackets to clamp two housebricks to the spindle will help a lot. As will using a real spindle.
I built a big folding CNC machine about 3 years ago. https://youtu.be/bksUuudEVfo
Waiting for the foldable vacuum cleaner that comes along with it…
What a horrible video. 3 minutes of grinding, then the vacuum cleaner and no view of the product. WTF?